Is-it standard to ignore null values?

[nfilotto]

Hi All,

During my investigation, I noticed that Infinispan ignores null values. Maybe I misunderstand the contract of a Map but I thought that if a map implementation doesn't support a null value, it is supposed to throw a NullPointerException otherwise it is supposed to take into account the null value. In case of inifinispan it seems to ignore it which cans be dangerous when we first put a non null value then we try to put a null value, so we believe that the current value is null but in fact it is still the non null value. If it is forbidden we expect a  NullPointerException otherwise cache.get should return null, do you agree with my assumption?

I tried the following code with the most common implementations of a Map such as HashMap, ConcurrentHashMap, LinkedHashMap, Properties and WeakHashMap and for all of them the test case described below pass:

{code}

   private void testNullValue(Map<String, String> cache) throws Exception

   {

      System.out.println("Test Null Value with " + cache.getClass());

      boolean supported = false;

      try

      {

         cache.put("a", null);

         // Null value supported

         supported = true;

      }

      catch (NullPointerException e)

      {

         // Null Value not supported : OK

      }

      catch (Exception e)

      {

         fail("Only NullPointerException is allowed");

      }

      System.out.println("The map of type " + cache.getClass() + " " + (supported ? "supports" : "doesn't support")

         + " null values");

      cache.put("a", "b");

      try

      {

         cache.put("a", null);

         // Null value supported

         if (supported)

         {

            assertNull("As " + cache.getClass()+ " supports null value we expect 'null' as value", cache.get("a"));

         }

         else

         {

            fail("'null values' are not supposed to be supported by " + cache.getClass());

         }

      }

      catch (NullPointerException e)

      {

         // Null Value not supported : OK

         if (supported)

         {

            fail("'null values' are supposed to be supported by " + cache.getClass());

         }

         else

         {

            assertEquals("As " + cache.getClass()+ " doesn't support null value we expect 'b' as value", "b", cache.get("a"));

         }

      }

      catch (Exception e)

      {

         fail("Only NullPointerException is allowed");

      }

   }

{code}

The same test case fails with infinispan since null values are ignored. I attached the full Test Case.

Thank you for your answers,

BR,

Nicolas